The invention relates to torque sensors for cylindrical shafts subject to torque.
Torque sensors are known in the art, including magnet-elastic torque sensors, for example as shown in Garshelis U.S. Pat. Nos. 4,760,745 and Hochstein et al 4,712,432 and 4,712,433. In these types of sensors, magneto-elastic material on the shaft exhibits changing magnetic permeability with changing stress and strain as the shaft is torqued. The changing permeability is sensed, and is indicative of torque.
The present invention provides an improved magneto-elastic torque sensor incorporating both electrical and magnetic properties to provide improved signal strength and larger differential signals between stressed and strained conditions as the shaft is torqued.
The invention also relates to a torque sensor relying upon electrical properties of a conductive loop on a shaft subject to torque.